Our house's floor

is what I tend to hear most of the time

e.g. the floor of our house

However, the phrase "the house floor was clean", would be considered correct as well, but I would say that using "the house's floor" is what most speakers would say.

Our house's floor

is what I tend to hear most of the time, meaning:

the floor of our house

However, the phrase "the house floor was clean", would be considered correct as well, but I would say that using "the house's floor" is what most speakers would say.